What command allows the user to configure the V.25 (fast modem) upgrade rate?
A.
cnfvchparm
B.
cnfsysparm
C.
cnfchec
D.
cnfsigparm
Explanation:
The V.25 modem detector recognizes the steady 2100 Hz tone output by V.25 compliant modems and FAX machines to disable echo cancellers at the beginning of transmission. When a channel is declared V.25 modem, a message is sent to the controller card, and software coordinates upgrade the connection at both ends from ADPCM to PCM (unless already PCM, or otherwise configured in the “cnfvchparm V.25 Detect” field). Therefore, the connection effectively becomes “p” until the modem removal criteria (bi-directioinal power below “MDM Low Pwr Thrsh” for a duration greater than “MDM Detect Silence Max”) are met, at both ends, when it returns to the configured state. Software attempts to synchronize changes at both ends to within 100 msec, but there is a short silence on the channel while reconfiguration takes place.